Answer: The number of high school students who use e-cigarettes or other vaping devices jumped 78 percent in the last year, according to a 2018 survey by the U.S. Centers for Disease Control and Prevention. The FDA considers the levels at which teens use “electronic nicotine delivery systems” or ENDS to be an epidemic. Though the FDA moved to regulate the industry in 2016, the dates that manufacturers are required to comply with the regulations have been repeatedly extended. Meanwhile, teens continue to be attracted to the variety of candy-like flavors and the sleek and stealthy designs of the devices. Some ENDS look like pens or USB flash drives and, because they do not require combustion and do not produce smoke, teens can inhale discreetly with ease.

A: ENDS are battery powered and use liquid nicotine extracted from tobacco. The nicotine is mixed in a base of propylene glycol or vegetable glycerin — often with added flavors — and heated into vapor for users to inhale.

Q: But wait, isn’t vaping better than smoking tobacco cigarettes?

A: Most e-cigarettes contain nicotine, though it is possible to purchase e-liquids without it. Nicotine is a highly addictive stimulant tied to cardiovascular disease and other negative health outcomes. While vaping does not expose users to some of the harmful chemicals from tobacco combustion, the flavoring liquids can contain dangerous chemicals known to destroy lungs: diacetyl and 2,3-pentanedione. Some scientists have noted that inhaling vapor may deposit aerosol deeper into the lungs in areas more susceptible to damage from toxic substances. One recent study, published in the November issue of the American Journal of Physiology, found the flavoring chemicals in e-liquids caused significant inflammation in the lungs of mice and other serious damage.

Q: What are diacetyl and 2,3-pentanedione?

A: Diacetyl and 2,3-pentanedione are flavoring compounds hailed for their buttery taste. They are added to everything from chips and candy to cream cheese and ice cream. The chemicals are byproducts of fermentation and also form naturally in butter, beer and other foods. They have been deemed safe to eat in trace amounts, but studies show they can be toxic when inhaled. Diacetyl has been linked with lung disease and deaths of workers in microwave popcorn plants.

Q: Do all e-liquids contain diacetyl and 2,3-pentanedione?

A: It’s difficult to know for certain. A Milwaukee Journal Sentinel investigation found the testing methods used by some manufacturers do not always detect the chemicals. Some companies purport that their e-liquids are diacetyl-free when they are not. One researcher analyzed 159 e-liquid flavors from 36 manufacturers in seven countries and found as many as 70 percent of sweet-flavored e-cigs contain diacetyl, according to a 2014 report.